The fine and intermediate cone crushers which are now in use comprise an outside cone and a crushing cone disposed therein, with a crushing chamber formed therebetween. The crushing cone is mounted on a sperhical support which is secured, as is the outside cone, to the crusher bed. The crushing cone drive is provided with an unbalance means or eccentric. Mounted both on the both the outside and crushing cones are armours fashioned as detachable taper shells copying the shape of the respective cone. Due to considerable impact loads which occur in the crushing chamber, it is a device for fastening an armour to the crushing cone that is one of the most critical unit of a crusher.
Known in the art is a device for fastening an armour to the crushing cone of a crusher having an armour-clad outside cone and an armour-clad crushing cone mounted therewithin on a spherical support (cf. USSR Author's Certificate No. 410,808). The device comprises a pressure bush arranged on the upper end of the armour and shaped as a protective cap provided with lateral openings and it protects a nut disposed thereunder against failure. The nut provided with lateral openings is screwed on a threaded shank of the cone, whose end face is provided with a diametral slot. The pressure bush and the nut are locked against the shank of the cone with a taper pin fitted in the shank slot and in the lateral openings of the nut and bush.
In mounting the armour on the cone, the nut is screwed on its shank to a predetermined position with respect to the end face of the armour, until openings of the nut coincide with the diametral slot of the cone shank. The pressure bush is also mounted so as to align the openings with the openings of the nut and with the slot of the cone shank. The locking taper pin is driven in the aligned openings of the pressure bush and nut as well as the slot of the shank. The position of the nut in height is predetermined so as to ensure an interference fit of the armour after the pin is driven, and to align the nut openings with the slot of the cone shank.
When replacing the worm armour, the operations are carried out in reverse order.
However, because of the necessity to lock the nut only in a predetermined position with respect to the slot of the cone shank, it is impossible to provide a uniform and adequate initial interference fit of the armour. As the armour becomes worn out, the interference is impaired, which results in a failure of the fit surface of the cone and its subsequent malfunction.
Besides, the device is complex in design.
Known in the art is a device for fastening an armour to the crushing cone of a crusher having an armour-clad outside cone and an armour-clad crushing cone mounted therein on a spherical support (cf. USSR Author's Certificate No. 304,975, Int. cl. B02c 2/04). This device also comprises a pressure bush arranged on the upper end face of the armour and shaped as a cap to protect a nut disposed thereunder against a failure, the nut being provided with openings and is screwed on the threaded cone shank. The pressure bush and the nut are locked against each other with a taper pin. The device differs from the abovementioned device in that it has no diametral slot on the end face of the cone shank. In this case, the taper pin doesn't lock the pressure bush and nut against the cone, but locks the bush against the nut only. This enables self-tightening of the armour as its fit becomes loosened.
Assembling and disassembling of the device are carried out in the same manner as in the above-mentioned device.
The wear of the armour results in a decreased rigidity of its shell, thereby loosening the interference fit down to its complete elimination.
In operation, the loosened armour of the crushing cone gets a slight radial shift against the cone and the shift passes in succession around the periphery of the fit surface of the armour.
With such a shift, the armour comes into slow rotation relative to the crushing cone and, under the action of a rising frictional force, carries along the pressure bush or cap contacting with the end face thereof, and also through the pin, rotates the nut that exerts, while tightening, through the same pin and the bush, a new force action upon the armour, causing it to reliably together up to an interference fit. The self-tightening occurs regularly in course of the armour wear, which eliminates failure of the fit surface of the cone body.
However, due to the necessity for an exact alignment of the openings in the nut and bush to receive the pin, the device fails to provide a required interference fit of the armour.
While disassembling the device, the pin is knocked out to eliminate the interference in the thread joint. This is hindered by the friction force in the pin seat that has increased many-fold as compared with the assembly interference due to elastic or plastic deformation of the pin. All of this fails to provide a joint which is capable of being easily disassembled.
Also known in the art is a device for fastening an armour to the crushing cone of an inertial crusher having an armour-clad outside cone and an armour-clad crushing cone mounted therewithin on a spherical support (cf. USSR Author's Certificate No. 507,356). The device comprises a pressure bush arranged on the upper end face of the armour and a screw placed in a threaded opening in the central area of the cone, which screw is provided with a central opening and a flange provided with threaded openings to receive the bolts and with a slot to receive a projection of the pressure bush. The pressure bush is bolted to the flange of the screw and is equipped with a protective cap secured thereon.
When assembling the device, the screw with the pressure bush is screwed into the threaded opening of the cone and, upon the contact of the bush with the armour end face, it is tightened with a force sufficient to ensure a reliable interference of the armour with the fit surface of the cone. The protective cap is then secured on the bush.
This device enables a reliable initial interference fit of the armour. At the same time, the device in question operates at a decreased self-tightening of the armour.
There is no need for a knock treatment of the screw in order to release it and replace the worn armour. The interference in the thread of the screw is released by unscrewing the bolts coupling it with the bush. Having done this, the screw can be easily removed by hand.
However, since the allowable tensile strength values are lower than the compressive ones, it is necessary to increase significantly the diameter of the bolts, considering the strength condition while in tension. The increase of the bolts in diameter is limited by the overall dimensions of the device, which results in an unreliable operation of the device.
Besides, a non-parallelism of the armour end face and the flange plane, results in the parts of the device often being subjected to deformations when securing the armour and when its self-tightening, which hinders the disassembly of the device, and, in specific cases, makes it inoperative.
Furthermore, the device is a complex design.